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Biology > Mitosis > Flashcards

Mitosis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Give three examples of regeneration

A
  1. Healing of wounds
  2. Growth of new tail after a lizard has lost its tail
  3. Continual replacement of dead cells of the outer layer of skin or dead blood cells
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2
Q

Why is regeneration possible?

A

Due to controlled mitotic division

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3
Q

Cells in the human body carried out regeneration continually and only when necessary

A

Continually: Skin cells

Only when necessary: Liver cells

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4
Q

What does ‘cell cycle’ means

A

The period beginning from the time a new cell is produces until the cell completes a division

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5
Q

Why is G1 (Growth phase) in Interphase important to a cell

A

Proteins and new organelles are synthesised

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6
Q

Describe why S phase (synthesis phase) is important to the cell

A

In this phase, the doubling of chromosomes (DNA replication) occurs when each chromosome duplicates to form two identical chromatids.

Both the chromatids separate into two different daughter nuclei.

This ensures that the diploid cells of the parents are maintained in daughter cells.

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7
Q

What are the subphases in Mitotic Phase

A
  1. Nuclear division phase/ Mitosis

2. Cytoplasmic division phase

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8
Q

How does the cytoplasmic division phase differ between animal cells and plant cells

A

In animal cells, cytokinesis occurs when the actin filaments in the cytoplasm contract, forming a cleavage furrow.

The cleavage furrow deepens until the cell separates into two daughter cells.

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9
Q

State two differences between the products of mitosis and meiosis

A
  1. Daughter cells have 6 chromosomes in mitosis and 3 chromosomes in meiosis
  2. Crossing over does not occur during mitosis but crossing over occurs during meiosis
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10
Q

Explain the role of meiosis in maintaining the diploid number of an insect

A

Insect reproductive organs will produce haploid gametes during meiosis.

During fertilisation, the nucleus of the male gamete (n) and the nucleus of the female gamete (n) will fuse to form a diploid zygote (2n)`

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11
Q

Role of mitosis in plant apical meristem

A

Increase cell number for growth

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12
Q

Role of mitosis in agriculture

A

Produce many new plants at a very fast rate

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13
Q

Importance of crossover in meiosis

A

Causes variation

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14
Q

Important events that occur at G1, S and G2 phase in Interphase

A

G1: High rate of biosynthesis of ribosomes, proteins and first growth phase

S: Replication of DNA

G2: Second growth phase and production of new organelles for cell division

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15
Q

Name all stages in M phase

A

Prophase, Metaphase, Anaphase, Telophase, Cytokinesis

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16
Q

One effect caused by uncontrolled mitosis

A

(Growth of tumour)

Cancer

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17
Q

One commercial application for knowledge of mitosis

A

In tissue culture, production of oil palm clone with desirable characteristics as parental plant

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18
Q

Two ways meiosis differs from mitosis

A
  1. In meiosis, during pairing of homologous chromosomes, chiasmata formation occurs during crossing over
  2. Meiosis: The chromosome number is halved when haploid cells form, two divisions are needed to complete process whereby four cells are formed
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19
Q

Importance of mitosis in living organisms

A
  1. Mitosis produces genetically identical cells.
    The daughter cells produced have the same function as the parent cell.
  2. Mitosis is also important for growth and repair of cells, and for asexual reproduction or clone formation.
  3. Mitosis enables rapid reproduction in favourable conditions
20
Q

How to identify between mitosis and meiosis

A

Mitosis: No reduction in chromosome number, both are diploid
Meiosis: Chromosome number is halved, both are haploid, crossing over has occurred

21
Q

Describe stage after metaphase

A

Anaphase

Chromatids separate when the centromere splits and the chromatids are pulled to opposite poles by spindle fibres

22
Q

What is interphase

A
  1. Growth, synthesis of organelles,
  2. Division of organelles, replication of DNA
  3. Cytokinesis (the division of the cytoplasm or formation of the cell plate in plants）
23
Q

What processes must occur in a cell before mitosis

A
  1. The replication of DNA and centrioles,
  2. The production of organelles,
  3. The synthesis of protein, RNA and nucleotides
24
Q

The stage which chromosomes split at the centromere

A

Anaphase

25
Q

The stage which chromosomes become visible

A

Prophase

26
Q

The stage which nuclear envelope reforms

A

Telophase

27
Q

The stage which chromatids move to opposite poles of the cell

A

Anaphase

28
Q

The stage which chromosomes line up among the equator of the spindle

A

Metaphase

29
Q

Difference between tissue culture and sexual propagation in plant propagation

A
  1. Tissue culture involves mitosis only, sexual propagation involves gametes which are produced by meiosis
  2. Tissue culture produces progeny which are genetically identical to the parent plant, while sexual propagation produces progeny with genetic variation
  3. Tissue culture can be done using tissue from many different parts of the plant, while sexual propagation involves flowers only
30
Q

Advantages of tissue culture than planting seeds

A
  1. Can produce a large number of progeny in a short time as seed production takes more time and some plants only produce a limited number of seeds
  2. If a parent plant with desirable traits is used, tissue culture produces progeny with the same desirable traits, while progeny from seeds have unpredictable traits
31
Q

Disadvantages of tissue culture than planting seeds

A
  1. Produces progeny with no variation, while plant from seeds have a genetic variation which is necessary for the survival of a population in a changing environment
  2. Produces progeny with a shorter lifespan compared to plants from seeds which live longer
32
Q

Common problems when cloning animals

A
  1. Low success rate
    (More than 90% fail attempts of cloning to produce viable offspring)
  2. Cloned animals tend to have defective immune functions and higher rates of infection, tumour growth and other disorders
33
Q

Describe changes during Metaphase I

A

Bivalents, which is composed of four chromatids, align at the metaphase plate

34
Q

Describe changes during Telophase I

A

Nuclear membrane and nucleolus may reform or the cell may quickly start Meiosis II

35
Q

What happens after Telophase I

A

The cell will undergo cytokinesis
Cytokinesis happens when a fibre ring composed of a protein called actin around the centre of the cell, contracts, pinching the cell into two daughter cells, each with one nucleus

36
Q

Importance of Prophase I

A

Crossing over occurs to exchange the genetic materials between non-sister chromatids of the homologous chromosomes, This gives rise to genetic variation in the offspring produced.

37
Q

Problem of using clones

A

Clones can be destroyed completely if they do not have the resistance to new diseases or pests due to lack of variation

38
Q

Why is DNA replication important in living organisms

A

It creates the next copy of DNA that have to go into one of the two daughter cells when a cell divides.

Without replication, each cell lacks adequate genetic content to give instructions for synthesis proteins vital for body purpose.

39
Q

Why is the structure (Bivalent) important

A

Crossing over occurs between non-sister chromatids of homologous chromosomes

40
Q

What happens at Prophase

A
  1. The chromosomes condense, thicken and become tightly coiled
  2. Each replicated chromosome consists of two sister chromatids held together at the centromere.
  3. Each pair of centrioles migrate to the opposite poles
  4. The nucleus disappears and the nuclear membrane disintegrates
41
Q

What happens at Metaphase

A

The chromosomes are arranged randomly at the metaphase plate with the two sister chromatids of each chromosome still attached to each other at the centromere

42
Q

Two factors of cancer cells

A
  1. Ionising radiation such as X-rays, ultraviolet rays and gamma rays
  2. Certain carbon compounds such as tar in tobacco smoke
  3. Carcinogenic (cancer-causing) compounds like Formaldehyde
43
Q

In terms of cell division, how the cancer cells come about

A

Due to the severe disruption to the mechanism which controls the cell cycle, cells divide by mitosis without control and regulation
This produces cancer cells which subsequently form disorganised lumps called tumours

44
Q

Ways to destroy or prevent cancer cells

A
  1. Radiotherapy is the use of radiation to kill cancer cells and shrink tumours. It works by damaging a cells DNA so much that the cell cannot divide
  2. Chemotherapy uses certain drugs, often in combination, to kill actively dividing cells
45
Q

What cause Trisomy/ Down syndrome

A

During meiosis I, the homologous pair of chromosome number 21 fails to separate
This results in an extra chromosome in one of the daughter cells at the end of the cell division
This daughter cell which forms a gamete, either a sperm or an ovum is fertilised by another normal gamete
Fertilisation produces a zygote with 47 chromosomes, 3 of which are chromosome number 21

46
Q

What is nutrient agar

A

A growth medium which consists of a complex mixture of nutrients such as amino acids and other substances such as hormones needed for the growth of tissues

47
Q

What is callus and explain how it is formed

A

A callus is an undifferentiated mass of tissues produced from an aggregate of cells through mitosis

Biology (9 decks)

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